If Mueller didn't charge Flynn and Manafort with collusion, then who was colluding?

All those charges, and none alleging that any of these men, some of them at the highest levels of the Trump campaign, took part in any collusion, or coordination, or conspiracy between the campaign and Russia.

“I can’t imagine that there would have been collusion or conspiracy with the Russians that Michael Flynn didn’t know about,” said Sol Wisenberg, a former prosecutor with the office of independent counsel Kenneth Starr. “If you’re trying to make a collusion case and you are Mueller, you’re trying to get someone to plead to the crime you’re trying to prove.”

McCarthy has written much the same. “When a prosecutor has a cooperator who was an accomplice in a major criminal scheme, the cooperator is made to plead guilty to the scheme,” he wrote last December. “This is critical because it proves the existence of the scheme.”

Even Preet Bharara, the New York U.S. attorney fired by Trump and no fan of the president’s, said last year, “When we had evidence against somebody and wanted them to flip, we made them plead guilty to every bad act that they had ever done, especially if we were later going to be alleging other people had engaged in that activity as well.”